1. Field of the Invention
The present invention relates to an capturing technique to capture an object with an angle of view that is wider than that of the capturing range (angle of view) of an optical system for a capturing device by a plurality of times, thereby obtaining a captured image of the entire object.
2. Description of the Related Art
An electric mount has been conventionally known as a device that is attached between a tripod and a camera and used to rotate the camera through a predetermined angle. The electric mount is employed as an auxiliary capturing instrument to capture, for example, a panoramic image. The electric mount rotates the camera through a predetermined angle, and therefore allows capturing with an accuracy higher than that in capturing while a person pans the camera at an arbitrary angle in his or her hands. As a technique which uses such an electric mount, a technique (for example, Japanese Patent Laid-Open No. 11-295783) to automatically capturing a panoramic image by controlling both the electric mount and the camera is known.
In this manner, to generate one panoramic image from a plurality of captured images obtained by a plurality of times of capturing (divided capturing) using the electric mount, it is necessary to connect the plurality of captured images. Hence, each image is captured to have overlapping regions with adjacent images, is matched in position with the adjacent images, and undergoes a blend process, thereby undergoing a connection process. This position matching is, for example, a process of obtaining the mean square error for each pixel in the overlapping region, and matching the positions of two images so as to minimize this error. The captured image contains an error due to lens aberration (image distortion), and may have large perspective distortion, depending on the capturing position. Hence, in image connection, the position of each image is matched with those of adjacent images after a process of correcting these errors due to lens aberration and perspective distortion. However, the size and shape of the image change upon the lens aberration correction and perspective correction, and the size of the overlapping region, in turn, changes. Conventionally, the amount of image deformation due to these types of correction is treated as an unknown amount, so divided capturing is performed upon setting unnecessarily large overlapping regions in advance to ensure overlapping regions sufficient for image connection.
A system which performs divided capturing of a work of art such as a painting or a folding screen using an electric mount and a digital camera, and connects the captured images, thereby archiving the resultant image as ultrahigh-resolution image data, and a system which prints this image data to obtain a copy of the work of art, are attracting a great deal of attention. In such systems, a work of art is desirably captured with cuts as small as possible in consideration of, for example, its deterioration upon irradiation with, for example, an electronic flash.
Unfortunately, the above-mentioned conventional divided capturing which uses an electric mount wastes some capturing cuts because capturing is performed upon setting unnecessarily large overlapping regions. In contrast, if too small overlapping regions are set, overlapping regions sufficient for an image connection process cannot be ensured due to image deformation upon lens aberration correction and perspective correction, thus making an appropriate image connection process difficult.